A baler is an agricultural implement which is used to gather crop material that has been deposited on the ground in swaths or windrows and to pack the crop into tied bales. Balers, which may be self-propelled but are more commonly towed by a tractor and driven by the power take off (PTO) shaft of the tractor, fall into two categories, namely, round balers and square balers. Round balers, as their name implies, produce cylindrical bales but this invention is concerned only with square balers that produce bales of square or rectangular section.
Square balers have a baling chamber of square cross-section with a reciprocating plunger at one end and open at the other end. An intake duct communicates with the baling chamber near its end closed by the plunger. Crop material is loaded into the intake duct by a pickup to form a slice of crop material. Once the slice has reached a desired density, a so-called stuffer transfers the slice into the baling chamber where it is compressed between the plunger and the crop material already present in the baling chamber. After a bale of the desired size has been formed by compressing several such slices, twine is wrapped around the bale and tied to complete the baling process. The baling chamber is longer than a single bale so that the tied bale remains within the baling chamber in order to offer the resistance needed to allow the next bale to be compressed. As square balers are known and well documented in the prior art, it is not believed necessary to provide further detail of their construction within the present context.
The present invention is concerned with the preparation of slices within the intake duct and with the transfer of the slices by the stuffer from the intake duct into the baling chamber.
The intake duct communicates at its upper end with the baling chamber and at its lower end with a packer or rotor. The packer or rotor has rotating blades or tines that propel the crop material picked up from the ground towards the upper end of the duct in order to achieve an even distribution and a constant density within each slice of crop material. Once the crop material attains a desired density within the intake duct, as determined by a sensor, a cycle of the stuffer is commenced to transfer that slice into the baling chamber.
The stuffer operates in the same manner as a rake and has two mechanically driven arms carrying a tine bar at their free end. The upper surface of the intake duct has elongated slots that allow the tines of the stuffer to enter into the duct to engage the crop material packed within it. The movement of the arms causes the tines to follow a generally kidney shaped path so that they sweep along the entire intake duct to push the slice into the baling chamber. On reaching the upper end of the intake duct, they are retracted from the intake duct and return outside intake duct to a position near the lower end of the duct in readiness for the next stuffer cycle.
A problem that can on occasions be encountered is that the packer cannot propel the crop material sufficiently into to the intake duct to achieve an even distribution within the intake duct. As a result, the crop material is denser near the packer than at its upper end near the baling chamber. Aside from creating bales of uneven density, there is risk that clogging may occur near the lower end of the intake duct.
U.S. Pat No. 6,050,074 teaches using the stuffer to assist in redistributing the crop material within the intake duct. This is achieved by operating the stuffer in one of two modes. In a first mode, the stuffer performs a short packer stroke so that it only displaces the crop material part way along the intake duct. In the second mode, the stuffer performs a full stuffer stroke to transfer the contents of the intake duct into the baling chamber.